The class of polymers of carbon monoxide and olefin(s) has been known for a number of years. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. 1,081,304 produced similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium salts as catalyst. Nozaki extended the process to produce linear alternating polymers in the presence of arylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has become of greater interest in part because of the greater availability of the polymers. These polymers, often referred to as polyketones or polyketone polymers, have been more recently produced by processes illustrated by a number of published European Patent Applications including 121,965, 181,014, 213,671 and 257,663. The process typically involves the use of a catalyst composition formed from a compound of palladium, cobalt or nickel, the anion of a strong non-hydrohalogenic acid having a pKa below 2 and a bidentate ligand of phosphorus, arsenic or antimony.
The resulting polymers are relatively high molecular weight materials having established utility as premium thermoplastics in the production of shaped articles such as containers for food and drink by procedures which are conventional for thermoplastic polymers. Although the linear alternating polymers are crystalline with well defined melting points, the polymers do tend to lose crystallinity to some extent when exposed to multiple cycles of melting and solidification (crystallization). This apparent loss of crystallinity results in decreases in certain of the desirable properties of the polymers. It would be of advantage to provide compositions of the linear alternating polymers which have been stabilized against such apparent loss of crystallinity and accordingly have a higher melt stability.
Incorporation of one of the components of the compositions of the invention, the partial zinc salt of the acidic polymer, in linear alternating polymers is known from copending U.S. patent application Ser. No. 338,701, filed Apr. 17, 1989. The polymer blends thus produced are said to have improved processability and impact resistance.